The set of geological processes that result in the expulsion of lava, pyroclastics, and the volcanic venting effects associated with volcanoes: hot springs, smoking, and fumaroles. Synonym to vulcanism.

The eruption of molten material or gas-driven solid fragments onto the surface of a planetary body. On icy moons the phenomenon is sometimes called cryovolcanism to distinguish it from silicate or sulfur volcanism.